// File: frontend/lib/api.ts (更新)
// Description: 添加调用助手和会话管理 API 的函数

import { Assistant, AssistantCreateData, AssistantUpdateData } from "@/types/assistant";
import axios from "axios";

// --- Types ---
export interface Session {
    id: string;
    title: string;
    assistant_id: string;
    created_at: string; // ISO date string
    updated_at?: string | null; // Add updated_at
}

// Message type from backend
export interface Message {
    id: string;
    session_id: string;
    sender: 'user' | 'ai'; // Or extend with 'system' if needed
    text: string;
    order: number;
    created_at: string; // ISO date string
}

// 聊天响应类型
export interface ChatApiResponse {
  reply: string;
  session_id?: string | null; // 后端返回的新 session id
  session_title?: string | null; // 后端返回的新 session title
}

// --- API Client Setup ---
const API_BASE_URL =
  process.env.NEXT_PUBLIC_API_URL || "http://localhost:8000/api/v1";

const apiClient = axios.create({
  baseURL: API_BASE_URL,
  headers: {
    "Content-Type": "application/json",
  },
});

// --- Helper for Error Handling ---
const handleApiError = (error: unknown, context: string): string => {
  console.error(`API Error (${context}):`, error);
  if (axios.isAxiosError(error) && error.response) {
    // 尝试提取后端返回的详细错误信息
    return (
      error.response.data?.detail || `服务器错误 (${error.response.status})`
    );
  } else if (error instanceof Error) {
    return error.message;
  }
  return "发生未知网络错误";
};

// --- Chat API ---
/**
 * 发送聊天消息到后端 (更新)
 * @param message 用户消息
 * @param sessionId 当前会话 ID (可以是 'temp-new-chat')
 * @param assistantId 当前助手 ID
 * @returns 包含 AI 回复和可能的新会话信息的对象
 */
export const sendChatMessage = async (
  message: string,
  sessionId: string,
  assistantId: string
): Promise<ChatApiResponse> => {
  try {
    const response = await apiClient.post<ChatApiResponse>("/chat/", {
      message,
      session_id: sessionId,
      assistant_id: assistantId,
    });
    return response.data; // 返回整个响应体
  } catch (error) {
    throw new Error(handleApiError(error, "sendChatMessage"));
  }
};

// --- Assistant API ---
/** 获取所有助手列表 */
export const getAssistants = async (): Promise<Assistant[]> => {
  try {
    const response = await apiClient.get<Assistant[]>("/assistants/");
    return response.data;
  } catch (error) {
    throw new Error(handleApiError(error, "getAssistants"));
  }
};

/** 创建新助手 */
export const createAssistant = async (
  data: AssistantCreateData
): Promise<Assistant> => {
  try {
    const response = await apiClient.post<Assistant>("/assistants/", data);
    return response.data;
  } catch (error) {
    throw new Error(handleApiError(error, "createAssistant"));
  }
};

/** 更新助手 */
export const updateAssistant = async (
  id: string,
  data: AssistantUpdateData
): Promise<Assistant> => {
  try {
    const response = await apiClient.put<Assistant>(`/assistants/${id}`, data);
    return response.data;
  } catch (error) {
    throw new Error(handleApiError(error, "updateAssistant"));
  }
};

/** 删除助手 */
export const deleteAssistant = async (id: string): Promise<void> => {
  try {
    await apiClient.delete(`/assistants/${id}`);
  } catch (error) {
    throw new Error(handleApiError(error, "deleteAssistant"));
  }
};

// --- Session API ---
/** 获取指定助手的所有会话 */
export const getSessionsByAssistant = async (
  assistantId: string
): Promise<Session[]> => {
  try {
    const response = await apiClient.get<Session[]>(
      `/sessions/assistant/${assistantId}`
    );
    return response.data;
  } catch (error) {
    // 如果助手没有会话，后端可能返回 404 或空列表，这里统一处理为返回空列表
    if (axios.isAxiosError(error) && error.response?.status === 404) {
      return [];
    }
    throw new Error(handleApiError(error, "getSessionsByAssistant"));
  }
};

/** 删除会话 */
export const deleteSession = async (sessionId: string): Promise<void> => {
  try {
    await apiClient.delete(`/sessions/${sessionId}`);
  } catch (error) {
    throw new Error(handleApiError(error, "deleteSession"));
  }
};

// 注意：创建会话的 API (POST /sessions/) 在后端被整合到了 POST /chat/ 逻辑中，
//当前端发送 sessionId 为 'temp-new-chat' 的消息时，后端会自动创建。
//如果需要单独创建会话（例如，不发送消息就创建），则需要单独实现前端调用 POST /sessions/。

// --- Message API (New) ---
/** 获取指定会话的消息列表 */
export const getMessagesBySession = async (sessionId: string, limit: number = 100, skip: number = 0): Promise<Message[]> => {
    try {
        const response = await apiClient.get<Message[]>(`/messages/session/${sessionId}`, {
            params: { limit, skip }
        });
        return response.data;
    } catch (error) {
         // Handle 404 specifically if needed (session exists but no messages)
        if (axios.isAxiosError(error) && error.response?.status === 404) {
            return []; // Return empty list if session not found or no messages
        }
        throw new Error(handleApiError(error, 'getMessagesBySession'));
    }
};